The microscope is a widely used tool for research and diagnostics, particularly in the field of cellular biology, cytology and pathology. Use of the microscope is well known for detecting cultured cells or tissues that are untreated or treated with imaging agents, reagents or drugs, and tissue samples collected from a normal or a diseased individual. For example, in cancer research, microscopic analysis helps in detecting and quantifying genetic alterations that result from the progression of cancer. Digital microscopes are used to examine cellular morphology, the expression of specific genes, (e.g., gene amplification, gene deletion, gene mutation), and the expression of encoded proteins. The microscopic analysis of individual cells or entire histological sections on tissue micro arrays is widely known.
Microscopy is routinely used for rapid investigations at the cellular and sub-cellular levels but there are limitations to conventional microscopy associated with subjectivity and repeatability. Systems have been developed to generate 2-dimensional (2D) images, but these often do not provide an entire representation of the sample due to the limitation in the depth of focus with conventional imaging techniques. Systems have also been developed that generate a composite image simulating an extended depth of focus, by acquiring multiple images at multiple focal planes and selecting and combining the best, in-focus portions of the images. However, the ability of such systems to rapidly generate a composite image, especially in real time, is limited because of the need to rapidly shift the focal position of the imaging system before capturing the digital images. The ability to rapidly generate a well-focused image is further limited by the need to post-process the stack of images into a composite image for viewing. Currently available digital imaging system and devices typically include cameras, piezo-objectives, piezoelectric stages, motorized stages, and linear objective turrets. However, none of these systems are capable of rapid image acquisition and generation.
An improved device for visual analysis of samples that combines the microscope with automatic imaging provisions with high focus quality and repeatability is desirable. There exists a need for an imaging system and a method for rapid focusing of an imaging system for obtaining a complete, in-focus, microscopic image over the entire thickness of the sample of interest, which may be used for static high-resolution object recapture as well as for continuous motion high resolution image viewing. Such an imaging system and method should desirably be cost effective, have relatively simple equipment requirements, and be readily adaptable to various magnifications.